Roulette bet with my friend

Hi

I've made a bet with a friend of mine over whether he can "section spin" on roulette. Unfortunately, I'm not talented mathematically enough to work out the true odds and I'm hoping someone can help me.

We both work in a casino and a friend of ours has a roulette wheel, he reckons he can hit a section 75 times out of 100 spins.

Let me explain the details:

It's a European roulette wheel -37 compartments (no double zero)
He has 18 numbers (roughly half the wheel) to get the ball to land in.
He must hit his section (18 numbers he's chosen) 75 times out of 100 spins
If he spins it 74 times he loses the bet

He believes he can hit a section, I doubt this. My only criteria is that the spins must be legal (and therefore to my reckoning, random)

What is the true odds that he can do that (assuming it's random and he has no special ability) and how do I work it out?

I've offered him 10/1 that he can't do it, and I'm guessing it's a very good price.

Much appreciated for any help given

Edd

Using the binomial distribution with a probability of success as 18/37, the chances of getting 75 or more successes in 100 trials are 14.56 million to 1. So yeah, I think you could gamble it up at 10 to 1.

Quote: englishedd

He believes he can hit a section, I doubt this. My only criteria is that the spins must be legal (and therefore to my reckoning, random)

I'm going to assume that the wheel is balanced and the tub is level, and the ball is fair (magnet test?).

Does the tub have frets?

What are the criteria for a "legal spin"?

Halves are a big section. Grand Voisins / tiers / orphelins wouldn't quite be fair, but actual thirds would be impressive.

Legal spins are standard rules for the UK:

The ball must revolve around the bowl at least 3 times
The wheel must be spinning
The ball must be spun in the opposite direction of the wheel

Other than that, basically anything goes.

Sodawater - thanks for your answer. The odds sounds much higher than I was expecting. Assuming it's all random and perfectly distributed over the 100 spins (a small sample I know) then I would expect to hit 18 numbers 48.65% of the time. But I'm surprised at how significantly higher the odds are.
So for my friend to hit an 18 number section in 100 spins 75 times (doesn't need to be sequential) is 14.56 million to 1? He doesn't stand a chance, I almost feel bad taking money off him!

Can you tell me how you worked it out?

Kind regards

Edd

Oh and Dieter, the wheel is fair, level and the ball is fair.

The roulette wheel is a standard European roulette wheel with the frets/obstacles in the way when the ball loses it's momentum.

Edd

What about the timing? Will he call the section, without ambiguity, before a dealer would say "no more bets" ?

Quote: DJTeddyBear

What about the timing? Will he call the section, without ambiguity, before a dealer would say "no more bets" ?

I was under the impression he was going to pick a specific half of the wheel before the 100 trials even began and he had to aim it. It seems to be about his aim rather than guessing the location based on the initial ball/wheel velocity.

If the wheel is leveled I'd assume he stands very little chance of success. But if you allow for a little tilting which will produce around 70-80 % ball drops on one and the same side of the rim and he really knows a little bit of dealer signature he might surprise you badly. Than again 75 out of 100 is a really HUGE target. If I was him I'd go for ~ 60-65 out of 100. And its still tough.

He is a cashier (previously a dealer) and was drunkenly boasting about his ability to spin a section, I jumped on this opportunity to make some money. So he will be spinning the ball (from the last number) and alternating directions every spin.

He has picked the section he will be attempting to spin, from number 22 anti-clockwise to 17 inclusively (18 numbers). So it's all decided beforehand, no changing of sections.

I'm really not a believer of section spinning or a dealer having a "signature". If a dealer could control where that ball went, even slightly by a few percent, they would work for 6 months and walk away a millionaire, and certainly not tell anyone.

You get videos like this


But to me this is just an example of how to waste a weekend! Plus he never spins from the other direction.

Edd

Quote: englishedd

Legal spins are standard rules for the UK:

The ball must revolve around the bowl at least 3 times
The wheel must be spinning
The ball must be spun in the opposite direction of the wheel

Other than that, basically anything goes.

If he can look at the wheel when releasing the ball, he might have a shot. I can believe he could practice a controlled ball launch, eyeball the rotor speed and position, and do some aiming at half the wheel.

Keep the rotor spinning, and good luck.

On this particular wheel setting/conditions from the video he could have alternate directions and still maintain very high hit ratio,I would guess, - its all to easy to do it under controlled conditions.

In real casino environment where the drop zone is rarely so strong is different matter. But there are favorable conditions out there as well.

The dealer signature is not much about the dealer, its about consistent rotor speed and dominant drop zone. Whether we believe in it or not is irrelevant to the physics. And the physics dictate that when a dominant drop zone is present it will group significant enough part of the ball speeds into a tidy cluster of similarly timed spins.

Combine that with a consistent rotor speeds and release point along with manageable scatter and you have yourself in a sweet spot. I know, it sounds like too many variables to work in your favor, but you might be amazed how often it happens compared to what skeptics believes.

In your case if the conditions are far not that much favorable I agree you have a great bet.

How deep are the pockets?

Quote: AxelWolf

How deep are the pockets?

This would definitely benefit the "dealer" if they're deeper as there might be less "random bouncing" if he could even hit a particular section.

So after watching this video, unless I'm missing something perhaps you can shoot a section as a dealer?

Quote: englishedd

Sodawater - thanks for your answer. The odds sounds much higher than I was expecting. Assuming it's all random and perfectly distributed over the 100 spins (a small sample I know) then I would expect to hit 18 numbers 48.65% of the time. But I'm surprised at how significantly higher the odds are.
So for my friend to hit an 18 number section in 100 spins 75 times (doesn't need to be sequential) is 14.56 million to 1? He doesn't stand a chance, I almost feel bad taking money off him!

Can you tell me how you worked it out?

Kind regards

Edd

Yup, assuming a fair wheel, just plug in the numbers to here --

http://stattrek.com/online-calculator/binomial.aspx

Quote: Romes

This would definitely benefit the "dealer" if they're deeper as there might be less "random bouncing" if he could even hit a particular section.

So after watching this video, unless I'm missing something perhaps you can shoot a section as a dealer?

Yes the predicting person wants deep pockets to have any chance.

It's well known that when the wheel has a strong dominant ball drop, decent sized frets and reasonable scatter that the wheel can be exploited.

I should also point out that the cards in the video dampen the ball a great deal since they absorb the energy of the bouncing ball.
However, if you watch carefully, you can see that the ball is striking the target area, which still demonstrates success.

Quote: Keyser

It's well known that when the wheel has a strong dominant ball drop, decent sized frets and reasonable scatter that the wheel can be exploited.

I should also point out that the cards in the video dampen the ball a great deal since they absorb the energy of the bouncing ball.
However, if you watch carefully, you can see that the ball is striking the target area, which still demonstrates success.

Maybe I can't tell because of my roulette newb eyes, but are these deeper pockets? I recall seeing deeper ones years back and much shorter ones now days at my local shops. Still, I'm not sure if the ones in the video would be considered deep, or short.

The wheel looks like a Cammegh Connoisseur with some kind of custom turret.

It's still considered to be a low profile. The pockets aren't deep, but are deep enough.

You are correct, in the past the pockets were much deeper, and there were larger ball deflector diamonds, and more of them on the apron of the wheel.

The deep pocket wheels began disappearing in the early 1990s because the visual ballistic players/wheel watchers were decimating the game throughout Europe.